This invention relates to the fabrication of synthetic logs by the compaction and interbonding of particles, particularly organic particles containing natural ligno-cellulosic resins.
The production of synthetic fireplace logs from organic particles such as sawdust, peanut hulls, vegetable fiber, etc. has been heretofore proposed. Attention is directed to U.S. Pat. No. 1,873,596 issued Aug. 23, 1932 to Jones; U.S. Pat. No. 1,990,631 issued Feb. 12, 1935 to Bowling; U.S. Pat. No. 3,227,530 issued Jan. 4, 1966 to Levelton; U.S. Pat. No. 3,240,573 issued Mar. 15, 1966 to Eyre, Jr.; and U.S. Pat. No. 3,506,415 issued Apr. 14, 1970 to Paladino, for examples of proposals in this area. In a typical operation, organic particles are initially compacted by a tapered auger during conveyance toward a die cavity. At the front of the auger, a pressure face is provided in which there is formed a narrow feed slot leading to the die cavity. A cutting edge adjacent the slot cuts the compacted particles into a narrow ribbon which is fed into the die chamber. The ribbon enters the die chamber in helical form and is engaged from behind by the pressure face such that successive layers of the ribbon are pressed together into the shape of a log. Aligned axially with the auger is an abutment head which abuts a front end of the log and applies a backpressure which resists advancement of the log, and causes the layers to become compacted together. In order to sever the log into segments, it is necessary that a time consuming retraction of the abutment head be performed, that spindle rotation be stopped and that a die wheel be indexed to the next position.
One of the more serious problems that has been previously encountered during operation of log forming machines concerns the generation of heat and steam. Excessive heat can char the organic particles, and steam trapped within the log can actually cause the log to explode. Heat and steam build-up has previously been facilitated by the use of tapered feed augers whose screw threads lie closely adjacent the surrounding housing walls. Consequently, there exists a tendency for back-ups to occur in the feeding system which generate high levels of heat as well as excessive initial compaction by the pressure face. Such action frequently results in equipment damage. Further heat generation can be caused as the compressed particles are cut into a narrow ribbon at the feed slot. Actually, when the cutter edge adjacent the feed slot becomes dull, horsepower consumption is raised and the rate of heat production increases dramatically. The high levels of heat generation not only can cause charring and explosion of the logs, but also necessitate the use of a high capacity cooling system to alleviate overheating conditions.
It is, therefore, an object of the present invention to provide methods and apparatus for more effectively producing logs from loose organic particles.
It is another object of the invention to provide methods and apparatus for producing logs from loose organic particles, which minimize the generation of heat and steam.
It is a further object of the invention to provide novel methods and apparatus for the continuous production of logs from organic particles at varying degrees of compaction.